Hi Dave,
I hopefully will provide a clear answer to your question and at least
for the two of us end the circle.
On May 12, 2008, at 4:14 PM, Dave Singer wrote:
>
> This entire conversation seems to be be in repeating circles.
> Personally, I would like to see a considered answer to the question
> below, and I don't think I have. Having, in essence, the question
> or disagreement endlessly repeated is making the mailing list
> tedious to follow. If we've had a helpful answer, can someone
> repeat it? If we're on track for getting an answer, can we wait for
> it? If we don't think an answer is possible, then we need to re-
> frame the question.
>
> "In striving for the best support for accessibility, we would like
> guidance on what to say in a specification on the use of the alt
> attribute for an image when there is no reasonable alt text known.
> It seems as if alt="" would state (probably erroneously) that the
> image is not semantically significant, and alt="an image" -- or
> something similar -- while true, is quite unhelpful. Some of us are
> uncomfortable with such a string, because it seems to mislead the
> user agent into believing that there is useful alt text, when it may
> be able to do better if it was aware that there is no alt text. For
> example, it can conclude quite easily by itself that it is "an
> image" and in addition would be able to state its size, and would be
> at liberty to do other analysis (e.g. stating that it had some
> similarity to another image on the page, recognize that it contains
> one or more faces, etc.). It can also do this in the user's natural
> language, if known. Because of this, we have considered allowing
> the omission of alt in this case (when no useful alt text is known
> at the authoring point), but we are concerned about this too, as it
> may 'open the barn door' and such a permission to omit may be
> abused. In essence, we have three cases (useful text known, images
> that are semantically insignificant, potentially significant images
> with no known alt text) but only two indicators -- non-empty and
> empty alt text? Do you have guidance on what to say in a
> specification on the use of the alt attribute for an image when
> there is no reasonable alt text known?"
The alt attribute is only one specialized attribute for non-text
media. For this case it should most likely be alt='' (for legacy
reasons especially). However we have the longdesc attribute aria-
described-by and potentially aria-role or similar attributes to
provide the additional information needed. The alt attribute doesn't
have to do everything.
So an image that is on the page but not part of a link, not presenting
rich text, and not an icon â€” but still semantically important â€” would
simply have alt=''. Perhaps something like this for a vacation
photograph discussed on a blog:
<figure><legend>We made a sand castle a the beech</legend><img alt=''
role='meaningful' longdesc='descriptions#sandcastle' ></figure>
Such an approach would:
1) satisfy the requirements you raised
2) provide rich accessibility
3) provide partial machine conformance verification
4) degrade gracefully in existing UAs
5) be easily generated from bulk upload authoring tools
I hope that answers the question satisfactorily.
Take care,
Rob